Technical challenges with collection of subsea minerals for use in EV batteries can be overcome

Front-end engineering design study paves the way for development of new subsea mining riser system, ensuring feasibility, safety, and operational performance at ultra-deep water depths.

Energy companies around the world have increasingly adopted strategies to achieve a broader energy mix to meet global demand as well as to achieve net-zero carbon objectives. As part of this energy transition the use of electric vehicles is expected to continue to increase. A recent market study has indicated that the electric vehicle (EV) battery market is expected to grow by $ 44.24 billion during 2020-2024, a 24% compound annual growth rate over the forecast period [1] .

As highlighted in the EV leader, Tesla’s recent ‘Battery Day’, cobalt, manganese and other minerals are required to meet the requirements for battery production. Traditional land-based mining resources will be insufficient to source the materials required. Lithium, by contrast, is seen as widely available on land and one of the most prolific elements on our periodic table. Existing as well as new energy companies are beginning to focus on opportunities in the remote regions of the deepest parts of the world’s oceans that perhaps contain a solution.

Resting on the seafloor in areas like the Clarion Clipperton Zone (CCZ) between Central American and Hawaii are a type of polymetallic nodules which contain these minerals in greater concentrations than what is typically found on land.  Extensive environmental studies and frameworks are being carefully established by researchers and the U.N. International Seabed Authority to study and ensure that these nodules can be gathered by underwater tractors while avoiding impacts to the marine environment or marine life.

In addition to thorough environmental investigations, significant challenges exist to reach and transport these nodules to surface vessels from water depths as great as 6000 meters.  One company, Oil States Industries, in partnership with subsidiary RiserTec, is working with clients to support this energy transition with enabling technology.  The company applies more than 75 years of experience in deepwater offshore oil & gas to bridge gaps in subsea mining and is positioned to take the role as an integrator of complete subsea mining systems.

“As clients make the jump to explore the deepest parts of the ocean, many technical challenges arise.  Not unlike space exploration, ultra-deep deployment of a subsea mining riser system requires a highly engineered approach,” Brian Mizell, VP of Business Development at Oil States, explained.  “From the very beginning we are working with clients to understand their expected performance requirements sometimes for very extreme conditions at ultra-deep water depths.  In a recent paid study, we helped a major global client with an ambition to research and collect nodules at 4000 meters water depth to assess a number of potential options, to review multiple technical scenarios, and to develop a new subsea mining riser system, ensuring feasibility, safety, and operational performance at these ultra-deep water depths.”

Consideration of the tremendous weight of the long riser string which connects the gathering vehicle to vessel, application of all the dynamic loads applied to the system at such depth based on anticipated met-ocean conditions, mitigation of vortex-induced-vibrations (VIV), as well as operability of the system all needed to be considered.  A successful strategy would require a very robust system able to withstand these conditions. 

John Shanks, Managing Director of RiserTec noted, “During the study we were able to help the client establish a basis of design, identify initial options including layouts and configurations, provide an initial design along with global analysis, overcome the significant Vortex Induced Vibration (VIV) issues, and answer key questions about sensitivities, fatigue life, operating speeds, and emergency stop.”

During the study, multiple design iterations were performed to account for the strict design requirements, including potential VIV.  This process yielded an optimum configuration providing a safe, economic, efficient and robust solution over all operating conditions, including deployment and recovery of the riser system.

Following a rigorous technical evaluation and testing program, the team delivered significant value to the client and several positive outcomes through Oil States’ ability to mix theoretical modelling with physical interpretation of the configuration using extensive knowledge of complex riser arrangements, in-house knowledge and detailed engineering support of connector designs, as well as rapid test of different configurations.  Reduced interfaces and good communications between the teams enabled the design drivers to be quickly and easily understood by both engineering analysts and the hardware specialists.

Ultimately the team was able to work together with the client to resolve several key technical and operational factors necessary for successful subsea mining operations and the feasibility of the subsea mining riser system to withstand the extreme operating conditions at 4000 meters water depth was confirmed.

Ensuring that all thoughtful care and attention is given to establishment of environmental frameworks and that proper engineering technical assessments are completed for the safe collection of these nodules are two critical considerations in the future development of a responsible and environmentally-friendly subsea mining industry that will support the growth in electric vehicle battery production and the energy transition.

Author: Brian Mizell

October 19, 2020

[1] Source Business Wire news

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